JERSEY CITY — In the days after the 9/11 terror attacks, many parents shielded their children from the graphic images of destruction on TV.

Not Chris and Mary Pat Christie.

Although the attacks hit close to home — Mary Pat Christie worked two blocks from the twin towers, and their children had friends who lost parents that day — the couple let their oldest children, then 8 and 5, watch whatever they needed to see to understand the event.

"It happened. It’s the real world ... This is real life," the governor said. "They need to know that to be on guard."

It’s one thing for a parent to urge a child to be good — advice that risks being ignored, Christie said. But allowing children to witness evil at work helps them understand what happens when people reject goodness.

"Evil being shown to kids can be an inspiration to them to be good," he said.

After taking a family tour of the state’s new 9/11 memorial at Liberty State Park in Jersey City today, the Christies sat down for a wide-ranging discussion of how their family handled the tragedy. Two of the Christie children — Andrew, 18, and Sarah, 15 — can remember the day. Patrick, 11, was a baby, while Bridget, 8, wasn’t yet born.

The Christies had no immediate relative killed in the attacks. Still, 9/11 tragedies surrounded them: a friend from church was killed, a co-worker’s husband barely escaped, a teacher’s firefighter brother died; both the older children had classmates who lost parents, and Mary Pat herself evacuated Manhattan by ferry.

Mary Pat Christie’s small bond firm was a client of trading firm Cantor-Fitzgerald, so she knew many traders there who died that day. That made it difficult — but all the more meaningful — for her and her co-workers to return to work as soon as the Wall Street area was re-opened for business.

"We felt like we had to keep working in honor of the people who didn’t make it — because we were the lucky ones," she said, tearing up at the memory. "And so we worked hard at trying to do that, especially for the people in our business who died."

Her daily commute took her by the smoldering clean-up site, where the smell of rotting flesh still permeated the air. "It was terrible," she said.

She said that every day, she wanted to salute the construction workers she passed on her walk to her office.

Neither of the Christies was fearful of her returning to her work in Manhattan; Christie said he felt his main job was to listen to his wife at the end of the day when she talked about what she’d seen.

"She was very intent on wanting to go back. Mary Pat’s very tough, so I wasn’t worried about her dealing with it," the governor said. "But she also tends to keep things in, so I wanted to try to get her to talk about how she was feeling, because I didn’t want it to be a bigger problem down the road for her."

Andrew Christie said he never feared for his mother, either on the day of the attack or afterward. A teacher at Assumption School in Morristown reassured him his mother was okay — although it turned out she was had no idea whether it was true.

"He kept asking if it was going to happen again. Are they going to fly planes into the Empire State Building?" Christie recalled.

Mary Pat Christie said Andrew drew pictures of a plane crashing into a building and later, for a class project, made a poster about freedom that still hangs in their work-out room.

"I have very vivid memories of it," Andrew said. The family’s au pair tried to steer him away from televised news and documentaries about it, to no avail. "That was all I was watching on TV," he said.

Sarah, in kindergarten, said that while it took her months to understand all that had happened, she clearly remembers "a lot of craziness" at school that day.

John O'Boyle/The Star-LedgerGovernor Chris Christie and wife Mary Pat look for names of people they know who were killed at the World Trade Center during a tour of the 9/11 Memorial at Liberty State Park in Jersey City. Looking on are Christie's daughter Bridget, center, and son Andrew.

Later in the week, she was able to grasp some of the basics of the attack. "Once I actually figured out what had happened, I was asking, ‘What’s going to make them not do it again?’" she said.

The Christie children had a source of reassurance not available to most families: Having just been nominated to become U.S. Attorney for New Jersey, Christie could tell his kids he and others were working hard to help prevent another attack. (One of the hijacked flights originated from New Jersey, so fell under his jurisdiction.)

After he’d been confirmed, Christie would share with them in general terms how the government was making sure terrorists were denied access to money, or had their secret plans discovered. for example.

"I was able to talk to them about what was going on in ways that were a lot less threatening than talking about what was going on in Afghanistan," he said.

Those discussions probably need to continue for their younger two, Mary Pat Christie said. She noted that when she asked 8-year-old Bridget if she understood what the names on the memorial meant, "She just kind of shook her head."